In Phase I of this project, the in vitro bleeding time test (Platelet- Stat(TM)), was shown to be reliable, safe, and provisionally efficacious. Instrument design, reagent preparation, and data analysis methodologies were all improved to the point where we now believe that further development is justified. The Specific aims for Phase II are: design and construction of a clinical research instrument, definition of conditions which define the high and low shear regimes, preclinical testing of Platelet-Stat(TM) monitoring of high and low shear coagulation, and development of quality control procedures for operating regimes and components. Our emphasis in Phase II development is to apply the Platelet-Stat(TM) technology to the monitoring of drug effects on coagulation and to the monitoring of coagulation defects during cardiac bypass surgery. Bleeding is a complex medical problem. Methods which operate in only one shear regime or which provide only soluble inducers of platelet activation do not adequately model physiological hemostasis. The Platelet-Stat(TM) provides a uniquely physiological model of in vivo events. PROPOSED COMMERCIAL APPLICATION: Two million template bleeding time tests are done yearly. The template test is under utilized due to archaic design and unproven predictive value. A manufactured, simple, safe, automated and efficacious test with predictive value will encourage physicians to utilize this important test cost effectively.